package com.tyl.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;
/**
 * 操作数据库的公共类
 * */
public class BaseDao {
    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    //静态代码块，类加载时就初始化了
    static {
        Properties properties = new Properties();
        //通过类加载读配置文件
        InputStream is = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");
        try {
            properties.load(is);
        } catch (IOException e) {
            e.printStackTrace();
        }
        driver=properties.getProperty("driver");
        url=properties.getProperty("url");
        username=properties.getProperty("username");
        password=properties.getProperty("password");
    }

    // 获取数据库连接
    public static Connection getConnection() {
        Connection connection=null;
        try {
            Class.forName(driver);//加载驱动
            //连接数据库
            connection = DriverManager.getConnection(url,username,password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return connection;
    }
    //编写查询公共类
    public static ResultSet execute(Connection connection, PreparedStatement preparedStatement,String sql,ResultSet resultSet,Object[] params) throws SQLException {
        //占位符sql直接在后面执行就好
         preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            // Object占位符从1开始，但是数组下标从0开始，所以i+1之后再赋值
            preparedStatement.setObject(i+1,params[i]);
        }
        resultSet = preparedStatement.executeQuery();
        return resultSet;
    }

    //编写增删改公共类
    public static int execute(Connection connection,PreparedStatement preparedStatement ,String sql,Object[] params) throws SQLException {
         preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1,params[i]);
        }
        int i = preparedStatement.executeUpdate();
        return i;
    }

    //资源释放
    public static boolean closeResource(Connection connection, PreparedStatement preparedStatement,ResultSet resultSet){
        boolean flag=true;
        if(connection!=null)
        {
            try {
                connection.close();
                // GC垃圾回收
                connection=null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag=false;
            }
        }
        if (preparedStatement!=null){
            try {
                preparedStatement.close();
                // GC垃圾回收
                preparedStatement=null;
            } catch (SQLException e) {
                flag=false;
                e.printStackTrace();
            }
        }
        if (resultSet!=null){
            try {
                resultSet.close();
                // GC垃圾回收
                resultSet=null;
            } catch (SQLException e) {
                e.printStackTrace();
                flag=false;
            }
        }
        return flag;
    }
}
